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Interplanetary Planar Magnetic Structures

行星际平面磁结构

基本信息

批准号：
07640591
负责人：
NAKAGAWA Tomoko
金额：
$ 0.9万
依托单位：
Tohoku Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640591/
关键词：
planar magnetic structures interplanetary magnetic field interplanetary space active region expansions sakigake Yohkoh solar wind soft X-ray image

项目摘要

Planar magnetic structures in which interplanetary magnetic field vector takes almost all directions that are parallel to a plane are correlated with EXPANDING ACTIVE REGIONS on the Sun by using Sakigake solar wind data and Yohkoh soft X-ray images of the Sun. During the period from January to July, 1993, we could identify three typical planar magnetic structures with the active region expansions found by Uchida et al. [1992] in the Yohkoh soft X-ray images, from which loop-like structures of active-region corona expand outward repeatedly at speeds of a few to a few tens of km/s even in the absence of any sizable flares. The active region expansions are expected to play an important role in mass loss from the Sun. On the other hand, not all the active regions were observed as planar structures in interplanetary space. In 16 Sakigake observations of solar wind plasma whose solar sources coincided with active regions, 9 had non-spiral magnetic field including planar structures, high ion density or both of them, but the other 7 (44%) exhibited no significant difference from average solar wind with spiral field.Pressure gradient in the solar wind is examined as a candidate cause of planar magnetic structures. In five of Sakigake planar magnetic structures with no bulk-speed gradient, two were in the regions of pressure gradient but the others were not. Flattened, intertwined flux tubes of high-beta plasma (Crooker et al., 1996) are re-examined to model planar magnetic structures. In order to reproduce a planar magnetic structure, a large number of flux ropes with small helicity are required. Variation of field direction is mainly due to variation of orientation of rope axs, rather than to field rotations in each of ropes.

利用Sakigake太阳风数据和Yohkoh太阳软X射线图像，将行星际磁场矢量几乎平行于平面的所有方向的平面磁结构与太阳上不断扩大的活动区相关联。在1993年1-7月期间，根据内田等人发现的活动区扩展，我们可以识别出三个典型的平面磁结构。[1992]在Yohkoh软X射线图像中，即使在没有任何大耀斑的情况下，活动区日冕的环状结构也以几到几十公里/S的速度反复向外扩展。预计活动区的膨胀将在太阳质量损失中发挥重要作用。另一方面，并不是所有的活动区都是在行星际空间中被观察到的平面结构。在16个太阳源与活动区重合的太阳风等离子体的Sakigake观测中，9个非螺旋磁场包括平面结构、高离子密度或两者兼有，但另外7个(44%)与具有螺旋场的平均太阳风没有显著差异。在5个没有体速梯度的Sakigake平面磁结构中，2个位于压力梯度区，其余的不在压力梯度区。高β等离子体的扁平、缠绕的磁通管(Crooker等人，1996)被重新检验以模拟平面磁结构。为了重现平面磁性结构，需要大量螺旋度较小的磁通绳。场方向的变化主要是由于绳轴方向的变化，而不是由于每根绳的场旋转。